http://europepmc.org/abstract/MED/7579458
http://europepmc.org/abstract/MED/8558920
http://europepmc.org/abstract/MED/16086416
http://europepmc.org/abstract/MED/11178628
http://europepmc.org/abstract/MED/12816858
http://europepmc.org/abstract/MED/8701987